Law enforcement officials, as is typical practice when booking a criminal, capture rolled fingerprints and not just flat fingerprints. Rolled fingerprints are advantageous because the latent fingerprints left at a crime scene are not necessarily from the flat part of the finger, but could be from the sides of the finger. Rolled prints, because of their larger area, also have more minutia than flat prints, so in theory when matching a rolled print to the rolled print of the same finger, the matching accuracies should be higher. The downside is that rolled fingerprint acquisition using a conventional fingerprint scanner currently requires a trained officer to hold both the finger and the hand of a subject, and then to rotate both of them while the finger is touching the rigid platen of the fingerprint scanner. Since capturing good quality rolled fingerprints currently requires a trained officer to work with the subject, this is a labor-intensive process and typically not implemented for non-criminal biometric applications. Even with a trained operator, there is the risk of the finger sliding or skin in the finger bunching up and then releasing during a roll which can cause artifacts in the captured rolled print. Software in the fingerprint scanner must take individual images of the finger as it is rolling across the rigid platen surface and then electronically stitch these images together in order to arrive at a final rolled fingerprint image. Consequently, the frame rate of the present fingerprint scanners must be high enough to accommodate the speed at which a finger might be rolled across the platen surface.
U.S. Pat. No. 5,991,467 to Kamiko describes an image sensor with a flexible substrate which, while deforming along the shape of a finger to finger pressure, does not deform to capture a rolled-equivalent fingerprint that extends to (at or proximate to) right and left sides of a fingernail of the finger around a front of the finger, referred to herein as a nail-to-nail fingerprint. Further, even if such sensor were so flexible, mere pressure alone does not guarantee that the sensor would be properly positioned along the finger to enable capture of a rolled-equivalent fingerprint image. Accordingly, it would be desirable to provide a system, method, and apparatus for capturing rolled-equivalent fingerprint images with a flexible sensor alleviating the need for a trained operator, and simplifies the image processing that the current method of acquiring a rolled fingerprint images requires using a rigid platen fingerprint scanner.